The present invention relates to a rolling roll with variable profile and of tapered piston type.
In order to ensure satisfactory rolling operations for workpieces with any widths, various kinds of rolling means have been proposed and demonstrated. A typical example of them is a rolling mill having rolling rolls with variable profile. The rolling roll comprises a roll core on which a sleeve is fitted to define a liquid-tight chamber between an end of the sleeve and a corresponding end of the roll core. Fitted between the opposing surfaces of the ends of the sleeve and roll core, one of which is a tapered surface, is a ring piston or pistons each having a tapered surface complementary to or made into intimate contact with the first-mentioned tapered surface. With such arrangement, axial shift of the ring piston or pistons will cause radial expansion or compression of the end of the sleeve so that the roll profile may be varied into a desired shape.
With the rolling mill of the type having rolling rolls each fitted with the above-mentioned ring piston or pistons, control of the roll profile into a desired shape is assured by detecting and controlling axial position of the ring piston or pistons with a high degree of accuracy.
As mentioned above, the roll end is provided with one ring piston or a plurality of ring pistons. In the former case, the construction becomes simple; but control of the roll into a complicated shape cannot be attained. In the latter case, the construction becomes complicated; but control of the roll into a complicated shape can be attained by adjusting the positions of the ring pistons independently of each other.
FIGS. 1 and 2 show an example of a profile-variable roll equipped with three ring pistons at its each end.
A profile-variable roll 1 comprises a roll core 1a on which a sleeve 2 is shrinkage-fitted to define a barrel of the roll 1. A portion of the roll core 1a corresponding to a sleeve end 3 is defined as a stepped portion 4 having a diameter smaller than that of the sleeve 2 fitted on the roll core 1a and the inner periphery of the sleeve end 3 is tapered at a predetermined angle. Thus, a cylindrical space 5 is defined by the outer periphery of the stepped portion 4 and the tapered inner periphery of the sleeve end 3. In the space 5, a plurality of (three in FIGS. 1 and 2) ring pistons 6, 7 and 8 are fitted such that they are movable in the axial direction.
The outer peripheries of the ring pistons 6, 7 and 8 are so tapered that they are complementary to or made into intimate contact with the tapered inner periphery of the sleeve end 3. The outer peripheries of the ring pistons 6, 7 and 8 on the side adjacent to the sleeve end 3 are formed with ring grooves 12, 13 and 14 into which 0 rings 18, 19 and 20 are fitted, respectively.
A portion of the sleeve end 3 extending beyond the step portion 4 toward a journal box 21 has an inner diameter greater than the tapered inner periphery of the sleeve end 3 and has a threaded screw 22. A neck portion 24 smaller in diameter than the stepped portion 4 extends from the stepped portion 4 and is contiguous with a shaft 23. A seal ring 25 is fitted over the neck portion 24 and abuts at its one side surface on a stepped surface between the neck portion 24 and the stepped portion 4. An 0 ring 26 is inserted between the seal ring 25 and the neck portion 24 while another 0 ring 27 is inserted between the seal ring 25 and the sleeve end 3. A ring nut 28 is threadably engaged with the screw 22 to securely hold the seal ring 25 in position.
A space defined by the sleeve end 3 fitted with the ring pistons 6, 7 and 8, the stepped portion 4 and the seal ring 25 can be therefore maintained in a liquid-tight state. First to fourth oil chambers 29, 30, 31 and 32 are defined respectively on the side of the ring piston 6 away from the journal box 21, between the ring pistons 6 and 7, between the ring pistons 7 and 8 and between the ring piston 8 and seal ring 25 and are communicated with a working oil source (not shown) through respective oil passage 33, 34, 35 and 36 defined in the stepped portion 4 and neck portion 24.
Spiral grooves 37 and 38 are formed respectively on the inner and outer peripheries of the ring piston 6. The spiral groove 37 is communicated with the second oil chamber 30 while the spiral groove 38 is communicated with the first oil chamber 29. In like manner, the inner and outer peripheries of the ring piston 7 are respectively formed with spiral grooves 39 and 40, the spiral groove 39 being communicated with the third oil chamber 31 while the spiral groove 40 is communicated with the second oil chamber 30. The inner and outer peripheries of the ring piston 8 are respectively formed with spiral grooves 41 and 42, the spiral groove 41 being communicated with the fourth oil chamber 32 while the spiral groove 42 is communicated with the third oil chamber 31. These spiral grooves are so formed that they are not communicated with the ring grooves 9, 10 and 11 and the grooves 15, 16 and 17 formed on the ring pistons 6, 7 and 8. Reference numeral 43 represents a bearing; and 44, a bearing retaining plate.
With the rolling roll of the type described above, the working oil is supplied respetively into the oil chambers 29, 30, 31 and 32 to independently adjust the fitting conditions of the ring pistons 6, 7 and 8 so that the outer diameter of the end of the profile-variable roll 1 can be varied into a suitable complicated shape.
It follows therefore that when the rolling roll of the type described above is used, for instance, as a backup roll, the shape of the profile-variable roll 1 is deformed into a shape capable of absorbing a thermal crown of a work roll and the rolling operation is carried out with the sharply deformed portion of the backup roll being made into contact with the sharply deformed end portion of the thermal crown, whereby the pressing surfaces of the work rolls in contact with a workpiece being rolled can be maintained straight so that an article having a high degree of surface flatness can be produced.
The detection of the axial positions of the ring piston is made by detecting the pressure of the working oil in the hydraulic circuit for shifting the ring piston in the axial direction. However, frictional forces between the ring piston, the roll core and the sleeve are considerably high and tend to unstably vary so that in some cases the ring piston cannot be shifted in response to the pressure of the working oil. Especially in the case where a plurality of ring pistons are provided, it is difficult to confirm the actual positions of inward ring pistons so that the precise roll profile control in response to the control of the positions of the ring pistons has not been carried out so far.
The present invention was made to solve the above and other problems encountered in the prior art rolling rolls and has for its object to make it possible to detect the axial positions of the ring pistons so that a satisfactory roll profile control can be accomplished.